C21-dicarboxylic acid anhydride and size agents and sizing process

ABSTRACT

There is disclosed a dicarboxylic acid anhydride made from a C21-dicarboxylic acid having the following general formula   WHEREIN X AND Y ARE INTEGERS FROM 3 TO 9, X AND Y TOGETHER EQUAL 12, WHERE Z is a member of the group consisting of hydrogen and COOH, with Z one of each moiety. There is also disclosed a process for sizing paper which comprises intimately dispersing within wet pulp, prior to the ultimate conversion of said pulp into a dry web, a sizing agent which includes a C21-dicarboxylic acid anhydride.

United States Patent 1191 Bills CZI-DICARBOXYLIC ACID ANHYDRIDE AND SlZEAGENTS AND SIZING PROCESS [75 Inventor: Alan M. Bills, Summerville, S.C.

[73] Assignee: Westvaco Corporation, New York,

22 Filed: o.1s,1973

21 Appl. No.1 407,734

Related US. Application Data [63] Continuation-impart of Ser. No.254,626, May 18,

1972, abandoned.

[52] U.S. Cl. 162/179, 162/157 C, 162/181 B, 162/181 D, 260/546 [51]Int. Cl D2111 3/08 [58] Field of Search 162/158, 179; 260/546 [56]References Cited UNITED STATES PATENTS FOREIGN PATENTS OR APPLICATIONS1,032,363 6/1966 Great Britain 6/1964 Liggett 162/180 ,11 1 3,821,075 [41 June 28, 1974 Primary Examiner-S. Leon Bashore AssistantExaminer-William F. Smith Attorney, Agent, or Firm-Richard L. Schmalz;Ernest B. Lipscomb, I11

I [57] ABSTRACT There is disclosed a dicarboxylic acid anhydride madefrom a C -dicarboxylic acid having the following general formula 6Claims, No Drawings 1 CZl-DICARBOXYLIC ACID ANHYDRIDE AND SIZE AGENTSANDSIZING PROCESS CROSS-REFERENCE TO RELATED APPLICATION Thisapplication is a continuation-in-part of copending U.S. Pat. applicationSer. No. 254,626, filed May 18, 1972, now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to the preparation of synthetic hydrophobic cellulose-reactiveemulsions for sizing paper made from novel C -dicarboxylic acidanhydrides. More particularly, this invention relates to synthetic sizesmade from C -dicarboxylic anhydride alone or in combination with fattyacid anhydrides or sizing agents for use in the sizing of pulp and paperproducts.

2. The Prior Art Paper sizing, in general, is the process of modifying asheet of cellulose fibers to decrease the rate of penetration of aliquid. The liquid in question is normally water, but sizing againstother liquids, such as oils, can be accomplished. The most common methodfor sizing paper against aqueous liquids is rosin sizing. In commercialrosin sizing, the rosin is added to the pulp as a dispersion in water.Sizing is obtained ,by precipitating the rosin onto the fibers. This isaccomplished by adding alum and maintaining the pH of the pulp slurrywithin a critical pH range which is necessary to obtain good rosinsizing. Since the rosin size precipitate is only absorbed and held tothe fibers by a charge difference (pulp fibers are negatively charged,rosin-size precipitate is positively charged), there remains theopportunity for the molecules to desorb when in contact with water forextended periodsof time. This phenomenon in which the rosin moleculesflip" to expose their hydrophylic carboxyls to the water, allows waterto penetrate into the fibers. Thus, the paper, so sized, is notpermanently protected against penetration of water.

On the other hand, synthetic size becomes chemically bound to thecellulose during the drying of the paper, thus giving more permanency tothe size, since the size molecules are now no longer able to flip.Synthetic size is usually added to the pulp as an emulsion in cationicstarch, which also acts to retain the size on theanionic cellulosefibers. The retention can be imroved further by addition of otherretention aids, such as cationic agents, to the starch emulsion. Becausethe size molecule forms a covalent bond with the cellulose, thesynthetic size is more efficient than rosin size. Hence,

smaller quantities of synthetic size can be employed to rosion ofmachine parts is reduced by operating at near N neutral pH conditions.

There are, however, some major disadvantages of 1 synthetic size whichincludes, slipperiness of the finished paper, reduced drainage atneutral or slightly alkaline conditions thus slowing down they machine,poor availability of dyes useful at alkaline pH, and the criticalthreshold level of most synthetic sizes makes it viturally impossible toobtain low to moderate sizing either there is no sizing or there is hardsizing. This latter disadvantage of synthetic size has been the mainreason why they have not completely replaced rosin size in applicationswhere there is need for a low amount of sizing as in coated papers.

During the past 10 or 15 years a number of synthetic sizes have beenintroduced in the market place. Among these sizes include those coveredby U.S. Pat. No. 3,409,500 to E. Strazdins et al. and U.S. Pat. No.3,102,064 to O. B. Wurzburg et al. The former patent relates todistearic anhydride sizing while the latter patent relates to an alkylsubstituted succinic anhydride.

It is therefore the general object of this invention to provide a new C-dicarboxylic acid anhydride. Another object of this invention is toprovide improved sizing agents, whose use results in the preparation ofpaper which is characterized by its reduced water and ink absorption aswell as its resistance to aqueous acid and alkaline solution. A morespecific object of this invention is to provide a C -dicarboxylic acidanhydride paper size which gives a wide range of sizing as needed forfine paper on the one. hand and bleached board on the other hand Afurther object of this invention involves the use of C -dicarboxylicacid anhydridesizing agents which may be employed with a variety oftypes of paper pulp over a wide pH range.

Other objects, features and advantages of this invention will be evidentfrom the foregoing detail description.

SUMMARY OF THE INVENTION q A dicarboxylic acid anhydride made from a Cdicarboxylic acid having the following general formula wherein at and yare integers from 3 to 9, x and y together equal 12, where Z is a memberof the group consisting of hydrogen and COOl-ll, with Z one of eachmoiety. A process for sizing paper which comprises intimately dispersingwithin wet pulp, prior to the ultimate conversion of said pulp into adry web, a sizing agent as described above. The sizing agent may alsoinclude substantial amounts ofoleic-type acid anhydride and tall oilfatty acid anhydrides. Additionally, the sizing process may include theuse of cationic agents or other materials required for emulsifying,dispersing and improving retention of the size on cellulose fibers.

DETAILED DESCRIPTION OF THE INVENTION The novel sizing agents of ourinvention maybe described as the anhydrideof a carboxylic acidrepresented by the general formula wherein x and y are integers from 3to 9, x and y together equal 12, where Z is a member of the groupconsisting of hydrogen and COOl-l, with Z one of each moiety.

Although the isomers wherein x is 5 and y is 7 form a preponderance ofthe compositions, there are minor amounts of the C -dicarboxylic acidwhere the cyclohexene ring varies in position along the carbon chain.For the purpose of this specification, compositions having the generalformula shown above are termed C dicarboxylic acid.

The C -dicarboxylic acids used in this invention are produced fromlinoleic acid of various animal, vegetable and tall oil sources. The C-dicarboxylic acid may be made by reacting linoleic acid with acrylicacid and catalytic amounts of iodine. A process for making the C-dicarboxylic acids for use in this invention as set forth in US. Pat.No. 3,753,968 granted Aug. 21, 1973. When c -dicarboxylic acids are madefrom tall oil fatty acids according to the process in U.S. Pat. No.3,753,968, the reaction mixture is predominately 40 percent C,-dicarboxylic acid and 60 percent oleic acid. This mixture ofdicarboxylic acid and oleic acid may itself be converted to anhydridesand used to form the size. Another embodiment of this invention is tohydrogenate the C -dicarboxylic acid of the general formula whereby thedouble bond of the ring becomes saturated. There are numerous well knownmethods for accomplishing the hydrogenation. As another aspect of thisinvention, the C -dicarboxylic acid anhydrides may may be used in sizeemulsions with other anhydrides such as distearic anhydride.

The C -dicarboxylic acids are made into anhydrides by reacting the C-dicarboxylic acid in any number of processes using acetic anhydride,for example, as the anhydride reactant. The C -dicarboxylic acid andanhydride, a slight excess of anhydride is preferred, are mixed andheated to about the boiling point of the anhydride. The reaction iscontinued until all the C dicarboxylic acid has reacted. Any remainingfatty acid is stripped from the anhydride. The C -dicarboxylic acidanhydride is then made into a size emulsion by any conventional means.When other fatty acid anhydrides are included in the size, they aremixed with the C dicarboxylic acid anhydride, they may be used at from10 percent to 90 percent by weight of the C dicarboxylic acid.

The actual use of the sizing agents of this invention in the manufactureof paper is subject to a number of variations and techniques, any ofwhich may be further modified in light of the specific requirements ofthe practioner. lt is important to emphasize, however, that with allthese procedures, it is most essential to achieve a uniform dispersal ofthe sizing agent throughout the fiber slurry, thereby necessitating thatits addition to the pulp be accomplished with vigorous agitation.Uniform dispersal may also be obtained by adding the sizing agent in afully dispersed form such as an emulsion; or, by the co-addition ofchemical dispersing agents to the fiber slurry.

Another important factor in the effective utilization of the sizingagents of this invention involves their use in conjunction with amaterial which is either cationic in nature or is, on the other hand,capable of ionizing or disassociating in such a manner as to produce oneor more cations or other positively charged moieties. These cationicagents, as they will be hereinafter referred to, have been found to beuseful as means for aiding in the retention of the sizing agent as wellas for bringing the sizing agent in the close proximity to the pulpfibers. Sizing processes which include cationic agents, although not apart of this invention, may beused in conjunction therewith, using thematerials disclosed in the aforementioned U.S. patents, among others.

In order to obtain good sizing, it is desirable that the C -dicarboxylicacid anhydride be uniformly dispersed throughout the fiber slurry in assmall a particle size as is possible to obtain. One method foraccomplishing this is to emulsify the C -dicarboxylic acid anhydrideprior to its addition to the stock utilizing either mechanical means,such as high speed agitators, mechanical homogenizers, or ultrasonichomogenizers, or by the addition of a suitable elulsifying agent.

With respect to amounts, the sizing agents may be employed in amountsranging from about 0.05 to about 5.0 percent of the dry weight of thepulp in that finished sheet or web. Within this range the precise amountwhich is to be used will, of course, depend for the most part upon thetype of pulp which is being utilized, the specific operating conditions,as well as the particular end use for which the paper is destined. Thus,for example, paper which will require good water resistance willnecessitate the use of a higher concentration of siz-' ing agent thanpaper which will be used in applications where excessive sizing is notneeded.

Water resistance of the paper prepared with C dicarboxylic acidanhydrides is obtained by drying the resulting webs, sheets or moldedproducts. Drying involves heating the paper at temperatures in the rangeof from to C. for periods of from 1 to 60 minutes. The C -dicarboxylicacid anhydrides are successfully utilized for the sizing of paperprepared from all types of both cellulosic and combinations ofcellulosic with noncellulosic fibers. The cellulosic fibers which may beused include bleached and unbleached sulfate (kraft), bleached andunbleached sulfite, bleached and unbleached soda, neutral sulfite,semi-chemical, chemigroundwood, ground wood, and any combination ofthese fibers. These designations refer to wood pulp fibers which havebeen prepared by means of a variety of processes which are used in thepulp and paper industry. in addition, synthetic fibers of the viscoserayon or regenerated cellulose type can also be used.

All types of pigments and fillers may be added to the paper which is tobe sized with the novel C dicarboxylic acid sizing agents. Suchmaterials include clay, talc, titanium dioxide, calcium carbonate,calcium sulfate, and diatomaceous earths. Other additives, includingalum, as well as other sizing agents can also be used.

The advantages of using the C -dicarboxylic acid anhydride of thesubject invention are illustrated by comparison to the effectiveness ofrosin and fatty acid synthetic sizes, more particularly, therequirements of, e.g., milk carton board, coated papers, etc. Forexample, when using rosin size the amount of water resistance topenetration obtained is somewhat directly proportional to the amount ofrosin size applied to the paper up to a limit of about 2.0 percent addedrosin. On the other hand synthetic sizes are more efficient than rosinin that for a low amount of sizing, for instance, one part syntheticsize may replace 3-6 parts of a fortified rosin size to obtain the sameamount of water resistance. Furthermore, because synthetic sizes are notsensitive to pH they do not require additional acidic conditions and pHmay be adjusted to achieve optimum machine runability and the desiredpaper finish characteristics. However, at low sizing levels, the degreeof 5 V a synthetic distearic anhydride size, for example. From the abovediscussion it is easily seen that the size of this invention forparticular uses has advantages that are not obtainable with eitherpresently available synthetic sizes or rosin sizes.

The practice of this invention may clearly be seen in the followingexamples.

EXAMPLE 1 The following procedure is typical of that used to make C-dicarboxylic acid anhydride. One hundred fifty grams of C -dicarboxylicacid (0.532 moles) and 81.5 grams of acetic anhydride are mixed in a 500ml. three necked flask. The mixture is heated and refluxed to just belowthe boiling point of acetic anhydride (130 C.) and held at thattemperature. The temperature in the reflux column is maintained at theboiling point of the acetic acid. When the theoretical amount of aceticacid is collected, the reaction is stopped. The excess acetic anhydrideis stripped off by distillation at reduced pressure.

EXAMPLE 2 The following procedure was used to prepare the aqueouspaper-sizing C dicarboxylic acid anhydride emulsions. To 85 ml. of waterwas added 11.25 grams of cationic starch and cooked under constantstirring at 9597 C. for minutes. The cook was cooled to room temperaturewith agitation and transferred to a Monel semi-micro cup. To the cup wasadded 7.5 grams of a C ,-dicarboxylic acid anhydride made according tothe procedure of Example 1 and the cup placed in a Waring blender andemulsified for 3 minutes. The emulsion was immediately transferred to400 ml. of water in a one liter beaker with constant stirring. Exactly 1liter was made by adding deionized water.

Prior to addition to the pulp furnish, the emulsion was further dilutedwith 9 parts water to one part emulsion. The furnish should be at orunder 1.0 percent consistency. The desired quantity of diluted emulsionwas added to the furnish aliquot with light agitation, and mixed for 30seconds prior to sheet formation. The addition of 3.4 gm. of alum (dry)to the cationic starch between steps (2) and (3) gives improvedresistance to penetration of highly acid test solutions.

After sheet formation 1 .25 g. TAPPl standard handsheets), the sheetswere pressed according to TAPPI standard. The sheets were then drumdried for 5 minutes (2 passes) at 230 F. The sheets were conditioned at75 F. and 50 percent relative humidity for a least 2 hours beforetesting with the Photosize water test. The results are shown below.

% Size on CD. Pulp Photosize Test, Sec.

The results show that the percent of sizing of this invention added topulp may be easily controlled as shown by the slow rise in rate ofsizing obtained wjile still being highly efficient. This rate and degreeof sizing is particularly advantageous for making fine papers.

EXAMPLE 3 This example illustrates the sizing ability of C dicarboxylicacid anhydride mixed with 50 and percent respectively of a fatty acid,oleic-type anhydrides. The procedure for making the size emulsions wassubstantially the same as that used in Example 1. The results are shownbelow.

% Size on OD. Pulp 40% C -dicarboxylic Photosize Test The results showthat both C -dicarboxylic anhydride and mixtures of the anhydride andoleic type anhydride emulsions are effective sizing agents.

EXAMPLE 4 i Three hundred (300) grams of C dicarboxylic acid and 162.5grams of acetic anhydride were combined in a one liter flask set up witha gas inlet (N blanket) and H 0 condenser. This mixture was heated to140 C. (pot temperature) and held at that temperature while refluxing.The temperature in the reflux column varied slightly but remainedbetween about 1 12 C. and 130 C. The reaction was continued until 80.0cc of acetic acid had been collected. The excess acetic anhydride wasstripped off by distillation at reduced pressure and the C -dicarboxylicacid anhydride collected.

The C -dicarboxylic acid anhydride was then tested in hardwoodhandsheets for sizing effects. The procedure used to make aqueous papersizing emulsions containing the C -dicarboxylic acid anhydride was thatset forth in Example 2.

After sheet formation (1.30 grams TAPPI handsheets), the sheets werepressed. The sheets were then drum dried for 5 minutes (2 passes) at 230F. The sheets were conditioned at F. and 50 percent relative humidityfor at least 2 hours before testing with the Photosize water test. Theresults of an average of five sheets are shown below.

% Size on O. D. Pulp Photosize Test, Sec.

The results show that the percent of sizing of this invention added topulp may be controlled.

While the invention has been described and illustrated herein byreferences to various specific materials, procedures and examples, it isunderstood that the invention is not restricted to the particularmaterials, combinations of materials, and procedures selected for thatpurpose. Numerous variations of such details can be employed, as will beappreciated by those skilled in the art.

What is claimed is:

l. Dicarboxylic acid anhydride made by reacting a C -dicarboxylic acidhaving the formula CH-(Clhh-COOH wherein x and y are integers from 3 to9, x and y together equal 12, where Z is a member of the groupconsisting of hydrogen and COOH, with Z one of each moiety, and aceticanhydride.

2. The C dicarboxylic acid anhydride of claim 1 wherein said C-dicarboxylic acid is hydrogenated.

3. The method of sizing paper which comprises, intimately dispersingfrom 0.055.0 percent, based on the dry weight of the pulp, of a sizingagent within wet pulp, prior to the ultimate conversion of said pulpinto a dry web, said sizing agent which comprises a C dicarboxylic acidanhydride, said C -dicarboxylic acid having the structural formula CH=CHCH3 (CHzh-C H GEL-(CH2) :14 O OH CH-CH i.

wherein x and y are integers from 3 to 9, x and y together equal 12,where Z is a member of the group consisting of hydrogen and COOH, with Zone of each moiety.

4. The method of claim 3 wherein the sizing agent is in the form of anaqueous emulsion.

5. The method of sizing paper which comprises, intimately dispersingfrom 005-5 .0 percent, based on the dry weight of the pulp, of a sizingagent within the wet pulp, prior to the ultimate conversion of said pulpinto a dry web,

a. said sizing agent which comprises a C dicarboxylic acid anhydride,said C -dicarboxylic acid having the following formula i z Z wherein xand y are integers from 3 to 9, x and y together equal 12, where Z is amember of the group consisting of hydrogen-and COOH, with Z one of eachmoiety, and

b. from 10 to percent by dry weight of said C dicarboxylic acidanhydride from the group consisting of oleic acid anhydride, tall oilfatty acid anhydrides and stearic acid anhydrides.

6. A paper product having intimately dispersed with the wet pulpthereof, prior to its conversion into a dry web,

a. from 0.05-5.0 percent based on the dry weight of the pulp of a sizingagent which comprises a C dicarboxylic acid anhydride, said C-dicarboxylic acid having the structural formula,

acid anhydride and tall oil fatty acid anhydrides.

2. The C21-dicarboxylic acid anhydride of claim 1 wherein saidC21-dicarboxylic acid is hydrogenated.
 3. The method of sizing paperwhich comprises, intimately dispersing from 0.05-5.0 percent, based onthe dry weight of the pulp, of a sizing agent within wet pulp, prior tothe ultimate conversion of said pulp into a dry web, said sizing agentwhich comprises a C21-dicarboxylic acid anhydride, said C21-dicarboxylicacid having the structural formula
 4. The method of claim 3 wherein thesizing agent is in the form of an aqueous emulsion.
 5. The method ofsizing paper which comprises, intimately dispersing from 0.05-5.0percent, based on the dry weight of the pulp, of a sizing agent withinthe wet pulp, prior to the ultimate conversion of said pulp into a dryweb, a. said sizing agent which comprises a C21-dicarboxylic acidanhydride, said C21-dicarboxylic acid having the following formula
 6. Apaper product having intimately dispersed with the wet pulp thereof,prior to its conversion into a dry web, a. from 0.05-5.0 percent basedon the dry weight of the pulp of a sizing agent which comprises aC21-dicarboxylic acid anhydride, said C21-dicarboxylic acid having thestructural formula,